888 research outputs found

    Reconstruction on trees and spin glass transition

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    Consider an information source generating a symbol at the root of a tree network whose links correspond to noisy communication channels, and broadcasting it through the network. We study the problem of reconstructing the transmitted symbol from the information received at the leaves. In the large system limit, reconstruction is possible when the channel noise is smaller than a threshold. We show that this threshold coincides with the dynamical (replica symmetry breaking) glass transition for an associated statistical physics problem. Motivated by this correspondence, we derive a variational principle which implies new rigorous bounds on the reconstruction threshold. Finally, we apply a standard numerical procedure used in statistical physics, to predict the reconstruction thresholds in various channels. In particular, we prove a bound on the reconstruction problem for the antiferromagnetic ``Potts'' channels, which implies, in the noiseless limit, new results on random proper colorings of infinite regular trees. This relation to the reconstruction problem also offers interesting perspective for putting on a clean mathematical basis the theory of glasses on random graphs.Comment: 34 pages, 16 eps figure

    Wind power variability and power system reserves in South Africa

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    Variable renewable generation, primarily from wind and solar, introduces new uncertainties in the operation of power systems. This paper describes and applies a method to quantify how wind power development will affect the use of short-term automatic reserves in the future South African power system. The study uses a scenario for wind power development in South Africa, based on information from the South African transmission system operator (Eskom) and the Department of Energy. The scenario foresees 5% wind power penetration by 2025. Time series for wind power production and forecasts are simulated, and the duration curves for wind power ramp rates and wind power forecast errors are applied to assess the use of reserves due to wind power variability. The main finding is that the 5% wind power penetration in 2025 will increase the use of short-term automatic reserves by approximately 2%

    Iterative qualitative approach to establishing content validation of a patient-reported outcome measure for arm lymphedema:the LYMPH-Q Upper Extremity Module

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    Background: Breast cancer-related lymphedema (BRCL) is one of the most common causes of upper extremity (UE) lymphedema in developed nations and substantially impacts health-related quality of life. To advance our understanding of the epidemiology and treatment of BRCL, rigorously developed and validated patient-reported outcome measures (PROMs) are needed. This study aimed to demonstrate the iterative content validity of a modular UE lymphedema-specific PROM called the LYMPH-Q UE module. Methods:A multi-step iterative qualitative approach was used. Semi-structured interview data from in-depth qualitative interviews with adult women (18 years and older) with BCRL were used to develop the first set of the LYMPH-Q UE scales. The content validity of these scales was demonstrated with patient and clinician feedback. Over the course of cognitive debriefing interviews, additional concepts of lymphedema worry and impact on work were identified as missing from the LYMPH-Q UE module. Subsequently, two new qualitative studies (a focus group and in-depth concept elicitation interviews with patients) were conducted, and two new scales were developed to measure lymphedema worry and impact on work life and their content validity was dResults: emonstrated. Qualitative data from in-depth and cognitive interviews with 15 (age 40–74 years) and 16 (age 38–74 years) women with BRCL, respectively, and feedback from 12 clinical experts, were used to develop and demonstrate the content validity of six LYMPH-Q UE scales measuring symptoms, function, appearance, psychological, information, and arm sleeve. Additionally, data from in-depth interviews with 12 (age 35–72 years) women with UE lymphedema and four focus groups (n = 16 women; age 35–74 years) was used to develop and assess the content validity of two new LYMPH-Q UE scales measuring lymphedema worry and impact on work life. The content validity of the previously established six scales was also demonstrated in these subsequent qualitative studies. Conclusion: The LYMPH-Q UE is a modular PROM developed using international guidelines for PROM development and can be used in clinical practice, research, and quality improvement to enhance patient-centered shared decision-making. This study’s innovative and iterative approach to content validation demonstrates that the LYMPH-Q UE is a comprehensive measure that includes important concepts relevant to patients with UE lymphedema.</p

    Biophotonics box: educational kit for multidisciplinary outreach activities in optics and photonics

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    The biophotonics box enables multidisciplinary/interdisciplinary and self-paced learning with at-home experiments using low-resource components. Experiments can increase the interest of students in STEM subjects by emphasizing the real-life applications in biology and medicine

    Recurrent structural variation, clustered sites of selection, and disease risk for the complement factor H (CFH) gene family

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    Data deposition: The data reported in this paper have been deposited as a National Center for Biotechnology Information BioProject (accession no. PRJNA401648). Author contributions: S.C. and E.E.E. designed research; S.C., C.B., L.H., K.P., K.M.M., M.S., A.E.W., V.D., T.A.G.-L., and R.K.W. performed research; S.C., J.H., C.B., L.H., K.P., K.M.M., M.S., A.E.W., V.D., F.G., A.J.R., R.H.G., T.A.G.-L., R.K.W., B.H.F.W., P.N.B., R.A., and E.E.E. contributed new reagents/analytic tools; S.C., B.J.N., J.H., and E.E.E. analyzed data; and S.C., B.J.N., and E.E.E. wrote the paper.Peer reviewedPublisher PD

    International mixed methods study protocol to develop a patient-reported outcome measure for all types of chronic wounds (the WOUND-Q)

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    INTRODUCTION: Most patient-reported outcome measures (PROM) for chronic wounds are specific to a single wound type (eg, pressure ulcer) or part of the body. A barrier to outcome assessment in wound care and research is the lack of a rigorously designed PROM that can be used across wound types and locations. This mixed method study describes the protocol for an international collaboration to develop and validate a new PROM called the WOUND-Q for adults with chronic wounds. METHODS AND ANALYSIS: In phase I, the qualitative approach of interpretive description is used to elicit concepts important to people with wounds regarding outcome. Participants from Canada, Denmark, the Netherlands, and the USA are aged 18 years and older and have a wound that has lasted 3 months or longer. Interviews are digitally recorded, transcribed and coded. A conceptual framework and preliminary item pool are developed from the qualitative dataset. Draft scales are formed to cover important themes in the conceptual framework. These scales are refined using feedback from people with chronic wounds and wound care experts. After refinement, the scales are translated into Danish and Dutch, following rigorous methods, to prepare for an international field-test study. In phase II, data are collected in Canada, Denmark, the Netherlands, and the USA. An international sample of people with a large variety of chronic wounds complete the WOUND-Q. Rasch Measurement Theory analysis is used to identify the best subset of items to retain for each scale and to

    US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

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    This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference
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